Abstract: A volume ventilator is disclosed which has a balloon valve type exhalation valve for permitting release of gases to the ambient environment during the exhalation period of artificial ventilation or spontaneous breathing, or when there is excess proximal pressure in the ventilator system. A pressure transducer continuously senses the proximal pressure in the ventilator system and sends to a microcomputer controller and associated circuitry of the ventilator system a signal indicative of the instantaneous proximal pressure. The pressure in the balloon, which is the pilot pressure of the exhalation valve, is regulated through a jet venturi type pressure controller which is connected to a source of pressurized gas. The gas flows through the jet venturi, wherein its flow rate is regulated by a ball valve moving against a suitable valve seat. The ball valve is controlled by a stepper motor through a cam follower.

Abstract: In an apparatus for encapsulating objects in molded plastic packages, an improved removable cavity plate assembly comprises upper and lower cavity plates which fit together in an interlocking manner to define molding cavities having integral surfaces formed within a single cavity plate on all sides of the cavity but one. The fourth side of each cavity is defined by a surface formed by the interlocking juncture between the two cavity plates. Plastic packages molded in the cavities thus are formed without a seam or parting line along the sides formed on the integral molding surfaces, the seam or parting line being formed only on the surface defined by the juncture of the two cavity plates.

Abstract: An external, self-contained laryngeal prosthesis is adapted for use by a tracheostomized patient having a surgically-formed "pseudoglottis" separating the trachea and the hypopharynx. The prosthesis includes a housing and a fitting for attaching the housing to the tracheostoma formed in the patient's neck. The housing contains an inhalation valve to allow inhaled air to pass through a first conduit into the trachea, and an exhalation valve for directing exhaled air from the first conduit into the housing downstream from the inhalation valve toward a second conduit. The second conduit is adapted for communicating between the housing and the hypopharynx through the fitting and through an incision in the pseudoglottis. Downstream from the exhalation valve is a tone-generating mechanism responsive to air pressures in a range normally produced by a speech effort.

Abstract: A pneumatic speech simulator has a vibratory tone-generating element which produces an audible tone in response to the flow of pressurized air within a predetermined pressure range, said tone being transmitted to a patient's pharyngeal region by a conduit, such as a nasal catheter. The simulator includes a pressure compensation valve, upstream from the tone-generating element, which maintains the pressure experienced by the tone-generating element within its operating range as the pneumatic resistance of tone-transmitting conduit is increased due to partial or total blockage.

Abstract: A gas flow measuring system employs an oscillating chopper valve alternately to deliver a flow head-generated pressure and a reference pressure to a pressure transducer. The chopper valve is driven by a stepping motor under the control of a microcomputer. The stepping motor drives the valve, with an oscillatory frequency determined by the microcomputer, between a first detented position, in which the flow head-generated pressure is delivered to the transducer, and a second detented position, in which the reference pressure is delivered to the transducer. The electrical signal produced by the transducer is fed to a sample-and-hold circuit, also under the control of the microcomputer, whereby the microcomputer controls the sampling rate of the sample-and-hold circuit. The microcomputer can thus establish an optimal sampling rate in accordance with the oscillatory frequency of the valve. In this manner, very fast sampling rates can be established, thereby minimizing the effects of zero drift in the transducer.

Abstract: A mechanism is provided for a respiratory ventilator by which the gas-delivery mechanism of the ventilator can be caused to deliver gas to the patient either at a predetermined flow rate or at a rate directly controlled by the patient's instantaneous demand. The mechanism includes a pressure-responsive device adapted to produce an analog signal indicative of the difference between a reference pressure and the patient's airway proximal pressure. The analog signal has a first polarity when the proximal pressure is less than the reference pressure in response to an inhalation effort, and a second polarity when the proximal pressure is greater than the reference pressure in response to an exhalation effort. A first control mechanism is provided which causes the gas-delivery system to deliver gas at a rate which is proportional to the absolute value of the analog signal when the signal has the first polarity and an absolute value at least equal to a predetermined threshold value.

Abstract: A ratcheting mechanism for a multiturn variable resistance device, of the worm screw-actuated type, has mutually engageable stopping members on the rotor and in the housing, limiting rotor travel beyond first and second limits. The stopping member in the housing has an inclined surface on one side which pivotally lifts the rotor against the force of the electrical contact spring (carried on one side of the rotor in contact with a resistive element), when the rotor reaches the first limit of travel. The pivoting action compresses the contact spring while allowing the spur gears on the rotor momentarily to disengage from the worm gear. This disengagement releases the spring, which then urges the rotor back into a gear-engaging position. The rotor is provided with at least one axially-shortened spur gear tooth positioned so as to be engageable with the worm gear when the rotor is at the second limit of travel.

Abstract: A patient adaptor fitting for a medical ventilator includes a jet pump having a nozzle receiving breathing gas from the inspiratory leg of the patient circuit, and a throat in communication with the expiratory leg of the patient circuit. Gas flows from the nozzle to the throat through a chamber in communication with the patient's breathing passages. The nozzle and the throat are dimensioned so as to produce a pressure drop in the chamber which balances the pressure drop through the expiratory leg of the patient circuit, thereby minimizing residual positive end expiratory pressure (PEEP) caused by the pneumatic resistance in the expiratory leg. The throat and nozzle dimensions are also selected so that the minimization of the residual PEEP occurs over a relatively wide range of flow rates into the nozzle.

Abstract: A gas flow rate control device for a medical ventilator includes a variable-orifice valve for adjustment of the peak flow rate, and a waveform regulator which supplies controlled gas pressure to the orifice. The regulator maintains a fixed pressure differential between the upstream side of the orifice and a reference pressure. The reference pressure is variable between atmospheric pressure and a pressure which is essentially patient airway proximal pressure. When the reference pressure is patient airway proximal pressure, a constant pressure differential is maintained across the orifice so that a uniform flow rate is maintained. When the reference pressure is atmospheric pressure, a constant pressure is supplied to the upstream side of the orifice, so that the flow rate from the orifice decreases as patient airway proximal pressure on the downstream side of the orifice increases.

Abstract: An apparatus which utilizes solid state piezoresistive strain sensing means to measure the static pressure as well as the differential pressure across a primary element, such as an orifice plate, venturi tube, nozzle or wedge.

Abstract: An incubating device particularly adapted for aligning an array of microscope slides bearing a tissue section, sample or specimen, and incubating the same with a series of test or reagent solutions at a higher-than-ambient temperature, is disclosed. The incubating device has a main body including a recess which substantially forms a tray in the main body. A plurality of substantially regularly spaced metal blocks are disposed in the recess, and a substantially flat upper surface of each metal block is adapted to receive and be in contact with a respective microscope slide.A heater is mounted underneath the main body to heat the main body, and to affect by direct conductance of heat, the heating of the metal blocks. A thermostat is mounted to the main body to monitor the temperature of the main body and to regulate the output of the heater in response thereto whereby the temperature of the metal blocks is maintained in a desired predetermined range.

Abstract: A servo-type gas pressure relief valve for regulating air pump pressure to pneumatic components of a medical ventilator or similar equipment utilizes a small diaphragm-type bleed or pilot valve to control the action of a main diaphragm valve. A small amount of inlet gas from the bottom side of the large diaphragm is passed through a restricted orifice to the top side of the large diaphragm. The bleed valve bleeds this gas to the atmosphere at a selected pressure, said bleeding action creating a pressure differential across the diaphragm of the main valve, which is thereby opened to exhaust gas to the atmosphere. A screw adjustment exerts tension on a spring which, in turn, exerts a force on the upper part of the bleed valve diaphragm. By adjusting the tension on the spring, the pressure at which air is bled to the atmosphere can be controlled, thereby accurately controlling the pressure at which the main valve opens.

Abstract: An apparatus which utilizes solid state piezoresistive strain sensing means to measure the static pressure as well as the differential pressure across a primary element, such as an orifice plate, venturi tube, nozzle or wedge.

Abstract: In a differential pressure transducer, of the type having a cantilever beam mechanically linked to a pressure-sensitive diaphragm, and piezoelectric strain gauges diffused into or bonded onto the beam, the beam has a relatively high compliance as compared with the diaphragm to facilitate operation in low pressure ranges and to increase the overall operating range of the unit. In addition, the beam is constructed so that the total bending energy is transmitted to the area of the strain gauges so as to achieve near-perfect operating efficiencies.

Abstract: A terminal lead for a miniature electronic component or the like includes an integral clip formed at one end for engagement with a substrate onto which the component has been deposited. The clip has a labyrinthine configuration which provides a secure grip on the substrate through extended length contact therewith. This extended length contact also reduces stress on the solder joint between the lead and a metallized contact area on the substrate, while also providing improved sealing with a molded plastic housing which encases the substrate.